The holey graphene oxide (HGO)was prepared by the method as
described previously [26]. Briefly, 100 mg GO was dispersed into
50 mL ultrapure water and treated by ultrasonication in a water
bath for 4 h, the homogeneous GO suspension (2 mg mL1) was
obtained. Then the GO suspension (50 mL, 2 mg mL1) was mixed
with 5 mL H2O2 (30%) aqueous solution, and refluxed at 100 C for
4 h. The as-prepared suspension was purified by centrifuging and
the sediment was washed with deionized water to remove the
residual H2O2, and then the sediment was re-dispersed in ultrapure
water by ultrasonication for 30 min to produce HGO suspension
with a concentration of 2 mg mL1. As a comparative experiment,
GO was also treated by the same method without adding H2O2.
PPy nanoparticles with average size around 150 nm were prepared
according to a modified oxidative polymerization method
[27]. Briefly, 0.2 g PVA was dissolved in 40 mL ultrapure water at
room temperature for 12 h, and then heated at 90 C for 1 h under
continuously stirring, followed by cool to room temperature. Then
2.48 g FeCl3$6H2O was added into the above PVA solution and the
system changed from a clear state to a yellow one. After stirring for
2 h, 280 mL Py monomerwas added into the yellow solution and the
polymerization process was controlled at 5 C for 4 h, the resulting
PPy nanoparticle precipitate was separated from the dispersion
solution by centrifugation (15,000 rpm, 40 min) and washed
several times with hot water.